Investigation of human enamel wear against four dental ceramics and gold

Objectives. This in vitro study compared the wear of enamel against aluminous porcelain, bonded porcelain, low fusing hydrothermal ceramic, feldspathic machinable ceramic, and cast gold. Methods. Fifty pairs of tooth-material specimens were tested in a dental wear machine, under a standard load (40 N), rate (80 cycles min(-1)) and for 25 000 cycles in distilled water. The amount of wear was determined by measuring the height loss of the tooth, and the depth of wear track of the restorative materials. Results. There was a significant difference in wear among the groups for both enamel and materials (p < 0.001). Follow-up comparisons (95% CI significance level) showed that gold caused significantly less enamel wear than all ceramics tested. The amount of enamel wear in the aluminous and bonded porcelain groups was significantly higher than with the hydrothermal and machinable ceramic groups. There was no significant difference between the amount of enamel wear produced by the aluminous and bonded porcelains nor between that produced by the hydrothermal and machinable ceramics. Furthermore, the wear of the aluminous and bonded porcelains was significantly greater than that of the hydrothermal ceramic, the machinable ceramic and gold. No significant difference in wear was found between aluminous and bonded porcelains, hydrothermal and machinable ceramics, or between machinable ceramic and gold. However, the hydrothermal ceramic had significantly greater wear than gold. Conclusions. It was concluded that the hydrothermal and the machinable ceramics were significantly less abrasive and more resistant to wear than the conventional aluminous and bonded porcelains. Gold was the least abrasive material and most resistant to wear, although the difference in wear between the machinable ceramic and gold was not statistically significant. (C) 1998 Elsevier Science Ltd. All rights reserved.